Protective masks have been used for sometime in both civilian and military applications. These protective masks are designed to protect the wearer from nuclear, biological, chemical agents, fumes, aerosols, gases and airborne contaminants. Hence, it is extremely important that the mask be properly tested to ensure that it will protect the wearer from these life-threatening agents.
It is often advantageous to test a protective mask without the protective mask being worn by an individual. Therefore, previously known mask testers have employed test heads about which a protective mask is mounted for testing. The disadvantages inherent in previously known test heads can have dramatic and adverse impacts on the mask testing process as explained below.
Previously known test heads used to test protective masks have been purposely designed to replicate the form of the corresponding region of the human head and neck. For example, test heads for face seal type protective masks take on the form of a human face while test heads for neck seal type protective masks replicate the human head and neck. Conventional wisdom of forming the test head such that the test head closely resembles the corresponding portion of the human body has significant and dramatic adverse consequences on the protective mask testing process. For example, test heads previously used to test neck seal type protective masks do not allow a neck seal type protective mask to be readily and properly installed over the test head. Rather, it is relatively time consuming and cumbersome to mount a neck seal type protective mask about previously known test heads configured to closely replicate the human head and neck region. This significant disadvantage severely limits the number of masks that can be tested in a given time interval. Further, it is not uncommon for a protective mask to be mounted about a conventional test head in such a manner as to prevent detection of a leak that is present in the mask, i.e., a fold could be present in the protective mask mounted on a conventional test head preventing detection of a leak located adjacent the fold.
Previously known test heads, also have significant and undesirable consequences of prolonging the period the mask tester takes to reach one or more prerequisite conditions (e.g., time to achieve a predetermined negative vacuum level before performing the leakage test), prolonging the response time (i.e., the time to determine whether a mask has passed or failed a given test once the test has been initiated) of the mask tester, dilution of the testing substance (e.g., challenge concentration) and creating an unacceptable lag time when a mask tester is in the probe mode.
Typically, the size of previously known test heads cannot be modified. Rather, where the size of the test head will not accommodate a particular size of protective mask, the test head must be removed from the mask tester and replaced with a differently sized test head. Thus, it is often the case that multiple test heads are required with a given mask tester to test differently sized protective masks.